Britton of the seventh (1916)

In 1876, Lt. Tony Britton of the 7th Cavalry is in love with pretty young Barbara Manning, but the wife of his superior, Capt. Granson, is in love with him and begs him to run away with her. Britton refuses, but is soon sent to arrest Sioux chief Rain-in-the-Face, who has murdered two soldiers from the 7th. He captures his quarry and carts him off to jail, infuriating the local Indians. When Capt. Granson learns of his wife's infatuation with Britton, he makes trouble for Britton, who is soon forced to resign his commission. He signs up as an army scout, and learns that the Indians are planning to attack and massacre the 7th under the command of Col. George Armstrong Custer. Can he get to Custer in time to warn him of the impending attack, and will he--a disgraced army officer--be believed?